1. Field of the Disclosure
The present disclosure is related to cooling systems, and, in particular, to automotive engine cooling systems.
2. Description of the Related Art
Typically, engines are either liquid-cooled or air-cooled. For air-cooled engines, the surface of the engine subjected to heating has air flow over a large area to remove the heat via convective/conductive transfer.
In a liquid-cooled engine, similar convective/conductive transfer takes place, typically via the liquid receiving the heat and then being moved, pumped, or otherwise transferred to a radiator or heat exchanger to release the engine heat to the surrounding atmosphere.
Most liquid-cooled engines control this heat exchange via a thermostat, which allows a “cold” engine, i.e., an engine that has not reached operating temperature, to allow a portion of the coolant to remain in contact with the heat transfer surfaces for a longer period of time, and, then when the engine/coolant reaches a certain temperature, the thermostat allows that liquid to be transferred to the heat exchanger and new liquid to contact the engine heat transfer surfaces. This allows the engine to reach operational temperature more rapidly.
A typical thermostat in an automotive engine is a bi-metal device that is closed until the bi-metal switch reaches a certain operational temperature, e.g., 185 degrees Fahrenheit, and once the operational temperature is reached, the thermostat opens and allows coolant to flow through the engine. The thermostat is typically placed between the engine and the automobile's heat exchanger, i.e., the radiator, and coolant is pumped from radiator to engine in a closed system to allow for engine cooling. Thermostats are typically either open or closed, depending on whether the bi-metal “opening” temperature has been reached to open the thermostat, and whether the “closing” temperature has been reached to close the thermostat. The range of operation of a typical thermostat is 10 degrees Fahrenheit, and once the temperature of the coolant is above that range, no control of coolant or engine temperature is possible.
As automobile engines are subjected to various external environments, such as winter weather that may be well below freezing and desert heat that may be well above 100 degrees Fahrenheit, a typical automobile thermostat is not able to distinguish between such extremes nor able to adjust to varying driving conditions, such as mountainous terrain or freeway driving. Further, a typical automobile thermostat cannot adjust for various engine intricacies such as individual engine peculiarities. Further, present day automotive thermostats do not allow for adjustment for fuel economy or increased performance of a given automobile without stopping the engine and removing the thermostat and replacing the thermostat with one that activates at a different temperature. The thermostat also represents a thermal single point failure in most engines. Potential solutions include, but are not limited to, removing the thermostat, installing water restrictor discs, and drilling bypass holes within the thermostat housing.
It can be seen, then, that there is a need in the art for a variable thermal control system. It can also be seen that there is a need in the art for a thermal control system that allows for changing the thermal control of a system during operation.